|Publication number||US7502613 B2|
|Application number||US 10/805,443|
|Publication date||Mar 10, 2009|
|Filing date||Mar 22, 2004|
|Priority date||Mar 24, 2003|
|Also published as||CN1287631C, CN1533210A, EP1463362A1, US20040192305|
|Publication number||10805443, 805443, US 7502613 B2, US 7502613B2, US-B2-7502613, US7502613 B2, US7502613B2|
|Inventors||Hideo Namiki, Yoshiaki Oomori|
|Original Assignee||Nec Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (16), Non-Patent Citations (4), Referenced by (8), Classifications (10), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to a wireless communication terminal and a control method thereof, and particularly to location registration operation of a wireless communication terminal capable of reducing a load on a network.
2. Description of the Related Art
In a cellular phone system, a base station is located for each location area. A cellular phone present in the location area performs location registration with the base station at a fixed time interval. Moreover, when power of the cellular phone is switched on, the cellular phone first performs location registration with the base station. When the cellular phone moves to another location area, the cellular phone performs location registration with a base station in the location area. When the location area includes a no service area and a service area, such location registration as described above is performed as soon as the cellular phone moves from the no service area to the service area.
Japanese Patent Laid-Open No. 2002-165260 discloses an example of location registration method of a cellular phone. In this example, when a network is in a congestion state, location registration is temporarily suspended based on information from the network. When detecting that the congestion state has been avoided, the cellular phone performs location registration. This method can reduce a load on the network situated in the congestion state.
However, even in the case where the network is not in the congestion state, when a plurality of the cellular phones perform location registration simultaneously, the load on the network is increased instantly, and there is a possibility that the congestion state may occur.
For example, in the case where there is a railway tunnel on a boundary between location areas, at an instant when a train comes out of the tunnel, cellular phones on the train perform location registration simultaneously in accordance with a change of the location area. At this time, a large load occurs instantly on the network. Moreover, when an audience having cellular phones comes out of a no service area such as a theater and a cinema, there is a possibility that location registration operations of a large number of cellular phones may occur nearly simultaneously. In this case also, the load on the network is increased temporarily, and there is a possibility that stable communications may come to be impossible.
A wireless communication terminal of an embodiment of the present invention includes: a random number generator; a timer; an operation unit; and a controller for controlling the wireless communication terminal. This controller can perform location registration based on random numbers outputted from the random number generator. The controller executes location registration when power of the portable wireless communication terminal is switched on, and thereafter, can execute the location registration based on the random numbers. Moreover, the controller can execute the location registration based on random numbers when the wireless communication terminal moves from a no service area to a service area. Furthermore, the controller can execute location registration based on random numbers when the wireless communication terminal moves to another location area. Each time interval between executions of location registration can be a sum of a predetermined period of time set in the timer and a period of time determined by random numbers.
An embodiment of a control method of a wireless communication terminal includes the steps of: detecting whether or not the wireless communication terminal can communicate with a base station; determining a time of executing location registration based on random numbers when the wireless communication terminal can communicate with the base station; and executing location registration in accordance with the determined time. In an example of this control method, location registration is repeatedly executed. Moreover, this control method can include the step of generating random numbers by activating a random number generator when the wireless communication terminal can communicate with the base station. It is possible to determine that the wireless communication terminal can communicate with the base station when the wireless communication terminal moves to another location area. It is possible to execute location registration when power of the wireless communication terminal is switched on and then to determine a time of executing location registration based on random numbers. It is possible to determine that the wireless communication terminal can communicate with the base station when moving from a no service area to a service area. Furthermore, when the wireless communication terminal remains in one location area, each time interval between executions of location registration is a sum of a predetermined period of time set in a timer and a period of time determined by random numbers.
According to the above-described wireless communication terminal and control method thereof, a load on a network is reduced when a large number of wireless communication terminals perform location registration simultaneously, and thus stable communications will be made possible.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description when taken with the accompanying drawings in which:
In the case where the fixed period of time T1 set in the timer 16 elapses while the cellular phone 10 is staying in a certain location area (YES in S24), the controller 11 allows the random number generator 17 to generate the random numbers Z (S25), restarts the timer 16, and thereafter, performs location registration in accordance with the same operation as above.
(1) Location Registration When the Cellular Phones are Turned On
The cellular phone MS3 is turned on at a time Ta. Thereafter, the cellular phones MS1 and MS2 are turned on simultaneously at a time Tb. The cellular phone MS3 starts location registration at the time Ta when being turned on. The cellular phones MS1 and MS2 start location registration simultaneously at the time Tb when being turned on. Thereafter, respective IDs of the cellular phones MS1, MS2 and MS3 and an ID of the location area B are registered in an administrative server.
(2) Periodic Location Registration
When a cellular phone keeps on staying in the location area B, as shown in the flowchart of
(3) Location Registrations When the Cellular Phones Move to Another Location Area
The cellular phones MS1, MS2 and MS3 move from the location area B to the location area A at a time Tf. Thereafter, in accordance with the flow shown in
As described above, the respective cellular phones determine the points of time of performing location registration by use of the random numbers Z. Accordingly, such an event where the points of time when the plurality of cellular phones perform location registration overlap with one another can be avoided. Therefore, simultaneous concentration of loads on the network can be reduced, and stable communications will be made possible. Particularly, in the case where a large number of cellular phones staying in the same location area move from the no service area to the service area substantially simultaneously, the present invention exerts an effect thereof.
While the present invention has been described in connection with certain preferred embodiments, it is to be understood that ht subject matter encompassed by the present invention is not limited to those specific embodiments. On the contrary, it is intended to include all alternatives, modifications, and equivalents as can be included within the spirit and scope of the following claims.
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|U.S. Classification||455/435.1, 455/422.1, 455/456.1|
|International Classification||H04W88/02, H04W60/04, H04W60/02|
|Cooperative Classification||H04W88/02, H04W60/02, H04W60/04|
|Mar 22, 2004||AS||Assignment|
Owner name: NEC CORPORATION, JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:NAMIKI, HIDEO;OOMORI, YOSHIAKI;REEL/FRAME:015122/0757
Effective date: 20040305
|Aug 15, 2012||FPAY||Fee payment|
Year of fee payment: 4
|Sep 11, 2014||AS||Assignment|
Owner name: LENOVO INNOVATIONS LIMITED (HONG KONG), HONG KONG
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NEC CORPORATION;REEL/FRAME:033720/0767
Effective date: 20140618
|Aug 25, 2016||FPAY||Fee payment|
Year of fee payment: 8